The long term objective is to analyze how dysfunctional muscle activity in the head and neck areas may be diagnosed with electromyographic (EMG) techniques and corrected using biofeedback training, occlusal and bitesplint therapy. The specific aims are to describe intramuscular electrode techniques in the TM joint and suprahyoidal areas after systematic anatomical studies on cadavers and to describe the functioning anatomy of the digastric and pterygoid muscles by EMG recordings with needle and fine wire electrodes. Incoordination of muscle activity during jaw and head movements, impaired ability to relax the muscles between novements, nonfunctional cocontraction and hyperactivity of muscles during e. g. bruxing, are dysfunctions with supposed significance for the etiology of pain and functional disabilities in various head and neck areas. TMJ patients frequently have tension headache and neck pain which quite often is relieved by occlusal or bite splint therapy. The attempts to use EMG as a diagnostic tool in the study of these dysfunctions have been restricted by insufficient knowledge about the functional anatomy of the relevant muscles and lack of techniques suitable for intramuscular EMG recordings. The normal variation of the morphology of the digastric, pterygoid and temporalis muscles will be recorded and needle techniques will be tested in fresh cadavers. EMG recordings with concentric and fine wire electrodes will then be made from the above muscles in subjects during jaw movements to provide a basis of normal EMG for future clinical studies.